This invention relates to laboratory sampling apparatus and more particularly to apparatus for obtaining samples from specimens of blood or the like contained in a series of closed containers.
Such apparatus are typically used in hospitals or commercial medical laboratories in performing various tests on specimens of whole blood or blood serum. Whole blood specimens are drawn from the patient and kept in glass tubes with rubber stoppers, such as those sold under the trade designation "Vacutainer" by Becton, Dickinson and Company of East Rutherford, New Jersey. In many cases the glass tubes also contain an anticoagulant. Before the blood in these tubes is analyzed, it is gently and carefully mixed to obtain an even distribution of blood cells. After mixing, a sample of each specimen is taken and subsequently analyzed as desired, e.g., analyzed for cell count or classification.
Sampling of blood serum is similar, except for the mixing step. A specimen of blood serum is typically obtained by separating it from whole blood in a serum separator tube such as those sold under the trade designation "Corvac" by the Corning Glass Works of Corning, New York. In these tubes a thixotropic gel barrier is formed between the blood serum and the other constituents of the whole blood specimen. Because of the presence of this thixotropic gel, it is not desirable to agitate such tubes. Blood serum specimens are, therefore, sampled and analyzed, but not mixed.
Current apparatus, however, are not without disadvantages. Apparatus which provide only a sampling function usually sequentially sample specimens placed in a linear or circular tray. In most of these, movement of the specimen tubes takes place in a generally horizontal plane, thereby taking up much valuable bench space. When blood serum is being sampled, these samplers require the use of some system for sensing the level of the liquid in the specimen tube. When whole blood is being sampled, these samplers must be used in conjunction with a mixer, a separate piece of equipment. The drawbacks of using two separate pieces of equipment, a mixer and a sampler, are readily apparent. The specimen tubes must be physically transferred from the mixer to the sampler, which wastes time and manpower. There is also the possibility that during this operation a specimen tube will be broken, lost or rendered otherwise unusable. Further, separate pieces of equipment require additional valuable laboratory space which is typically limited.
There are basically two types of separate mixers. One consists of a platen having grooves for receiving the specimen tubes. The platen and tubes are tilted or rocked slowly back and forth to mix the cells in the individual specimens. The second consists of a set of rollers between which the specimen tubes are manually placed. This second mixer mixes by simultaneously rotating and tilting the rollers.
Apparatus are also known which overcome some of the above-mentioned disadvantages of using separate mixers and samplers by including a mixing paddle in the sampler. The specimen tubes in such apparatus are open so that the mixing paddle can be introduced into the tubes to mechanically stir the specimens. These samplers also have a probe which is dipped into the specimens (after they have been individually mixed by the paddle) to aspirate samples therefrom.
Although open-tube mixer-samplers solve some of the problems arising from the use of separate mixers and samplers, they have other disadvantages. For example, the paddle will carry over blood from one specimen to the next unless it is washed between stirrings or is made of a water- and protein-repellent material. In addition, while inserting open specimen tubes into the mixer-sampler the sampler operator is exposed to the risk of contamination and infection, such as by hepatitis and other similarly transmitted diseases.
Representative patents which are of interest in the field of samplers include U.S. Pat. Nos. 3,607,097, 3,768,526, 3,832,140, 3,883,306, and 3,918,913. Also of interest is U.S. Pat. No. 3,431,886 which shows an apparatus for applying stains to microscopic slides and helical means for moving said slides in the apparatus.